Steam iron

ABSTRACT

A steam iron ( 500 ) comprises a housing ( 520 ) that includes a water tank ( 580 ), a steam chamber ( 600 ) and a pressure equalization conduit ( 7 60). The housing ( 520 ) includes an airing means ( 660 ). The steam iron is further provided with a mechanism for allowing air selectively into the water tank ( 580 ). The mechanism comprises a steam trigger ( 680 ) that is arranged to close or open the pressure equalization conduit ( 760 ) and the airing means ( 660 ) inversely. The mechanism may also comprise a spring loaded plunger or an electronic hand sensor.

FIELD OF THE INVENTION

This invention relates to a steam iron, more particularly to a pressure equalized steam iron.

BACKGROUND OF THE INVENTION

For a steam iron with a dosing point, water is introduced drop by drop from a water tank into a heated steam chamber. The steam, thus generated, passes out through steam outlet openings of a sole plate and comes into contact with a garment to be ironed. When the iron is placed on the garment, there is a restriction to steam flow and pressure builds up in the steam chamber. In order to equalize the pressure difference between the steam chamber and the inside of the water tank, the water tank and steam chamber are connected to each other by means of a pressure equalization tube. In such irons a constant steam rate is maintained as if the iron were freely suspended.

However, such systems have some practical issues such as steam condensation and overheating of the water tank. When the water in the water tank of the steam iron is moved back and forth during the active phase of ironing, water waves are formed in the water tank. These waves disrupt the pressure equalization. The steam that enters the water tank from the steam chamber is condensed on the tank wall by the water waves. With a volume ratio of approximately 1000 to 1 between water vapour and water, the condensation results in an undesirable under-pressure in the water tank and defeats the purpose of the pressure equalization. The pressure fluctuations in the water tank, which are generated by the wave movement of the water, also have a disadvantageous effect on the pressure equilibrium between the steam chamber and water tank and on the pressure present at the dosing point.

U.S. Pat. No. 6,745,504 provides a steam iron having a soleplate with a steam chamber and a water tank. A drip valve supplies the steam chamber with water from the water tank. The steam iron contains one or more one-way gas valves between the water tank and ambient air. These gas valves let air enter the reservoir in response to the under-pressure in the water tank caused by movement of water in the water tank. A pressure equalization conduit is formed in a manually operable rod of the drip valve, such that only one opening is required in the lower wall of the water tank. As the pressure equalization conduit is connecting the drip valve and the water tank, the entire water tank gets heated up because of steam passage. Further, using the gas valves to let the air into the water tank requires an additional design feature. The water movement during the normal ironing operation results in wave formation disrupting the consistent steaming performance.

Philips iron (HD1250) is provided with a pressure equalization conduit. In this iron, the water tank gets air/steam through the holes provided in the soleplate of the iron. During rest or during intervals when steaming is stopped, the condensed steam in the water tank is replaced by a mixture of steam and air from the soleplate. The steam in the mixture condenses and further creates under-pressure. Also the steam enters the water tank heating the entire water tank.

It is an object of the invention to provide a steam iron that mitigates the under-pressure in the water tank to give consistent steaming performance.

This object is achieved by the features of the independent claim. Further developments and preferred embodiments of the invention are outlined in the dependent claims.

SUMMARY OF THE INVENTION

In accordance with the invention, there is provided a steam iron comprising a housing that includes a water tank, a steam chamber and a pressure equalization conduit. The pressure equalization conduit equalizes the steam pressure between the steam chamber and the water tank. The housing includes an airing means. The steam iron is further provided with a mechanism for selectively allowing air into the water tank through the airing means. The air that is selectively let into the water tank, during the intervals between steaming, prevents under-pressure in the water tank that occurred due to the condensation of steam, thereby resulting in consistent steaming performance. Without this kind of concept, the steam rate would drop drastically over a period of time due to steam condensation in the water tank creating a vacuum. This concept prevents replacement of steam by steam and instead replaces part of the condensed steam by air. This keeps the partial pressure of steam lower in the space above the water and therefore further reduces the condensation rate and keeps the system steaming at a healthy rate.

According to another embodiment of the invention, the water tank is divided into a dosing chamber and a water reservoir by means of a partition wall. Separation of the water reservoir and the dosing chamber by the partition wall minimizes the waves inside the dosing chamber because of the smaller volume of water in the dosing chamber as compared to the entire tank. This ensures more consistent steaming as well as prevents the water reaching the pressure equalization conduit. The partition wall disallows waves and sloshing in the rest of the water tank to disturb the dosing chamber. This separation also keeps the heat restricted only to the dosing chamber.

According to a further embodiment, the dosing chamber is three to eight times smaller than the water reservoir. As a result, only a small amount of steam is used for pressure equalization. This minimizes rapid heating up of the entire water tank.

According to a preferred embodiment, the dosing chamber and the water reservoir are connected to each other by a means for communication. When the means for communication is opened, water can flow freely from the water reservoir to the dosing chamber.

According to yet another embodiment of the invention, the steam iron is provided with a mechanism for selectively allowing air into the space above the water in the water tank. This mechanism has a steam trigger that is arranged to open or close the pressure equalization conduit and the means for communication between the dosing chamber and water reservoir inversely. When the pressure equalization conduit is closed, the means for communication between the dosing chamber and the water reservoir is opened or when the pressure equalization conduit is opened, the means for communication between the dosing chamber and the water reservoir is closed. During ironing, when the steam trigger is actuated, the communication between the water reservoir and the dosing chamber is closed. This arrangement disallows waves and sloshing in the rest of the water tank to disturb the dosing chamber due to isolation from the water reservoir. Now the pressure equalization conduit is opened so that the steam from the soleplate can equalize the pressure. During this time, the flow of water from the dosing chamber into the soleplate is replaced by steam from the soleplate. The steam above the water in the dosing chamber condenses and creates an under-pressure. When the steam iron is at rest, the steam trigger is not actuated. In this situation, the pressure equalization conduit is closed and the means for communication between the dosing chamber and the water reservoir is opened. The water can freely flow from the water reservoir to the dosing chamber. The airing means allows air into the water reservoir which is followed by water gushing into the dosing chamber to compensate the under-pressure that is created during ironing. Since the connection to the soleplate is cut-off, further steam does not enter the dosing chamber.

According to another embodiment, the mechanism for selectively allowing air includes a spring loaded plunger. This acts as an actuator to open or close the pressure equalization conduit and the means for communication between the dosing chamber and water reservoir inversely. This provides a user friendly control of activating the pressure equalization phenomenon.

According to a further embodiment, the mechanism for selectively allowing air includes an electronic hand sensor. This can activate an electromechanical device such as a solenoid to open or close the pressure equalization conduit and the means for communication between the dosing chamber and water reservoir inversely.

According to yet another embodiment of the invention, the airing means allows air into the water reservoir only when the steam trigger is released and the steam iron is at rest. In other words, during the active phase of ironing, no water can flow from the water reservoir to the dosing chamber. Therefore, even when the airing means remains open during steam ironing, little or no air flows into the reservoir as the water quantity in the water reservoir remains the same and no replacement by air is needed.

According to still yet another embodiment of the invention, the mechanism for selectively allowing air into the water tank is provided with a steam trigger. The steam trigger opens/closes the pressure equalization conduit and the airing means into the water reservoir simultaneously, but inversely. When the steam trigger is actuated, the pressure equalization conduit is opened and water dripping onto the soleplate is replaced by steam from the soleplate. Part of this steam condenses inside the dosing chamber creating an under-pressure. When the iron is rested and the steam trigger is released, the pressure equalization conduit is closed and any under-pressure caused by steam condensation cannot be replaced by steam from the soleplate. Since the airing means is now open, air rushes in and compensates for the under-pressure by pushing water into the dosing chamber. Further, during ironing, as the airing means is closed, the water reservoir cannot receive air, the water in the dosing chamber remains at a constant level thus keeping the steam rate constant for a significant part of the ironing session. This minimizes the water waves in the rest of the water tank due to vacuum above the water level as air is not allowed into the water reservoir while steaming is done.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter and the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a steam iron during an active phase of ironing according to an embodiment of the invention;

FIG. 2 shows a steam iron in a rest position according to the embodiment of the invention as shown in FIG. 1;

FIG. 3 shows a steam iron during an active phase of ironing according to another embodiment of the invention; and

FIG. 4 shows a steam iron during a rest position according to the embodiment of the invention as shown in FIG. 3

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto. Any reference signs in the claims shall not be construed as limiting the scope. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. Where the term “comprising” is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun e.g. “a” or “an”, “the”, this includes a plural of that noun unless something else is specifically stated.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

In FIGS. 1 and 2, a steam iron 100 comprises a housing 120, which at its underside is closed by a soleplate 140. The soleplate 140 is provided with an ironing plate 160 at its bottom. The housing accommodates a water tank 180, a steam chamber 200, and a heating element 220 for heating the soleplate 140 and the steam chamber 200. Inside the water tank 180 is a partition wall 241 which divides the water tank 180 into a dosing chamber 240 and a water reservoir 260. The dosing chamber 240 and the water reservoir 260 are interconnected by a means for communication 280. The water tank can be filled with water via a filling port 300 at the front of the iron. The housing 120 is also provided with airing means 320 for allowing air into the water tank 180. When the means for communication 280 is opened, water from the water reservoir 260 enters the dosing chamber 240 and through the airing means 320 air enters the water reservoir 260. The steam iron 100 has a dosing point 340 through which water from the dosing chamber 240 passes drop by drop into the steam chamber 200. A steam regulator 360 can be accessed from the top outer side of the housing 120. The temperature of the soleplate is controlled by a thermostat 380. The thermostat 380 is mounted on the soleplate and is adjustable such that the user can set the temperature by turning the dial. The iron 100 is provided with a pressure equalization conduit 420 which is a tube connecting the top of the steam generation chamber 200 to the top of the dosing chamber 240, significantly above the water level in the dosing chamber 240 . The mechanism for selectively allowing air includes a steam trigger 400 which is situated at the top of the housing 120 as shown in the figure. This steam trigger 400 is connected to the linkages 242 and 243 communicating simultaneously with both the pressure equalization conduit 420 and the means for communication 280. The linkages 242 and 243 are arranged in such a way that the movement of the steam trigger closes and opens each connection respectively. More specifically, the arrangement facilitates closing of the means for communication 280 by pushing 243 down and opening of the pressure equalization conduit 420 by pushing 242 when the steam trigger 400 is depressed and vice-versa. In these figures the thick arrow indicates the flow of water, the arrow with dashes indicates the flow of steam and the other arrow indicates the flow of air.

In this embodiment, the steam iron 100 is provided with a steam jet 440 with which the user could choose to shoot steam from the front onto a garment through a nozzle by activating a steam deflector 460. The steam deflector 460 is a mechanical device that directs steam into the nozzle. The steam iron 100 is provided with a safety valve 480 which is a mechanical valve that opens at a pre-set excess pressure inside the water tank and releases steam from the front through the nozzle. This is a safety feature that might help release pressure under extraordinary circumstances where all the steam vents are closed or blocked and pressure builds up rapidly inside the water tank.

In FIG. 1, when the steam trigger 400 is depressed during ironing, the linkage 243 closes the means for communication 280 between the water reservoir 260 and the dosing chamber 240. This means that no water can flow from the water reservoir 260 to the dosing chamber 240. Therefore although the airing means 320 remains open during steam ironing, little or no air flows into the water reservoir 260 as the water quantity in the water reservoir 260 remains the same and no replacement by air thus is needed. The linkage 242 opens the connection between the pressure equalization conduit 420 and the dosing chamber 240 to equalize any pressure that is exerted. During this time, the water that flows from the dosing chamber 240 through the dosing point 340 into the steam chamber 200 and then on to the soleplate 140 is replaced by steam from the soleplate 140. This steam partially condenses inside the dosing chamber 240. As the interaction between the water reservoir 260 and the dosing chamber 240 is anulled during steaming, the steam stays inside the dosing chamber 240 and it results in only localized pressure equalization. As a consequence, heating is restricted only to the dosing chamber leaving the water reservoir cool.

In FIG. 2, when the iron 100 is rested and the steam trigger 400 is released, the linkage 242 closes the connection between the dosing chamber 240 and the pressure equalization conduit 420. The linkage 243 opens the means for communication 280 between the dosing chamber 240 and the water reservoir 260. The under-pressure, that develops when the steam above the water in the dosing chamber 240 condenses during the active phases of ironing, is overcome by water gushing into the dosing chamber 240 and air rushing into the water reservoir 260 via the airing means 320. Since the connection to the soleplate via pressure equalization conduit 420 is cut-off, further steam does not enter the dosing chamber 240. Thus air is used to overcome under-pressure in the water tank during the intervals of rest. This concept also ensures that the waves in the water reservoir 260 do not affect the dosing chamber 240 during ironing, thereby minimizing the fluctuations in steaming.

The mechanism for selectively allowing air in may include a spring loaded plunger (not shown) instead of a steam trigger. The spring loaded plunger acts as an actuator to open/close the connection between the pressure equalization conduit 420 and the dosing chamber 240 and the means for communication 280 between the dosing chamber 240 and the water reservoir 260 inversely. One end of the plunger is connected to linkages 242 and 243 communicating simultaneously with both the pressure equalization conduit 420 and the means for communication 280. The other end of the plunger protrudes from the housing 120 of the steam iron 100. When the plunger is depressed during rest, the linkage 243 opens the means for communication 280 between the water reservoir 260 and the dosing chamber 240 and the linkage 242 closes the connection between the dosing chamber 240 and the pressure equalization conduit 420. During ironing, when the plunger is released, the linkage 242 opens the connection between the dosing chamber 240 and the pressure equalization conduit 420. The linkage 243 closes the means for communication 280 between the dosing chamber 240 and the water reservoir 260.

The mechanism for selectively allowing air in may include an electronic hand sensor (not shown) instead of a steam trigger or a spring loaded plunger. The electronic hand sensor may be a capacitive sensor, an inductive sensor or the like. This sensor activates an electromechanical device such as a solenoid. The electromechanical device is connected to the linkages 242 and 243. During ironing, when the electronic hand sensor senses the hand of the user on the hand grip, the electronic hand sensor actuates the electromechanical device which in turn activates the linkage 242 that opens the connection between the dosing chamber 240 and the pressure equalization conduit 420. The linkage 243 closes the means for communication 280 between the dosing chamber 240 and the water reservoir 260. During rest, the linkage 243 opens the means for communication 280 between the water reservoir 260 and the dosing chamber 240 and the linkage 242 closes the connection between the dosing chamber 240 and the pressure equalization conduit 420.

In FIGS. 3 and 4, a steam iron 500 comprises a housing 520, which at its underside is closed by a soleplate 540. The soleplate 540 is provided with an ironing plate 560 at its bottom. The housing accommodates a water tank 580, a steam chamber 600, and a heating element 620 for heating the soleplate 540 and steam chamber 600. Inside the water tank 580 is a partition wall 590 which divides the water tank 580 into a dosing chamber 582 and a water reservoir 584. The dosing chamber 582 and the water reservoir 584 are interconnected by a means for communication 586. The water tank 580 can be filled with water via a filling port 640 at the front of the iron. The housing 520 is provided with an airing means 660 which is connected to a steam trigger 680 in such a way as to facilitate the air to go into the water tank 580 when the steam trigger 680 is not depressed and completely blocking any air flow into the water tank 580 when the steam trigger 680 is depressed. The steam iron 500 has a dosing point 700 through which water from the dosing chamber passes drop by drop into the steam chamber 600. The steam iron 500 is provided with a steam regulator 720 at the other end of the dosing point 700 which can be accessed from the top outer side of the housing 520. The temperature of the soleplate is controlled by a thermostat 740. The thermostat 740 is mounted on the soleplate and is adjustable such that the user can set the temperature by turning the dial. The iron 500 is provided with a pressure equalization conduit 760 that is basically a tube connecting the top of the steam generation chamber 600 to the top part of the dosing chamber 582, significantly above the water level in the dosing chamber 582. The steam trigger 680 has a linkage 681 to communicate with the pressure equalization conduit 760, arranged in such a way that the depression of the steam trigger 680 opens the pressure equalization conduit 760 and vice-versa. The steam iron 500 is provided with a steam jet 800 with which the user could choose to shoot steam from the front onto a garment through a nozzle by activating a steam deflector 810. The steam deflector 810 is a mechanical device that directs steam into the nozzle. The steam iron 500 is provided with a safety valve 820 which is a mechanical valve that opens at a pre-set excess pressure inside the water tank and releases steam from the front through the nozzle. In these figures the bold arrow indicates the flow of water, the arrow with dashes indicates the flow of steam and the other arrow indicates the flow of air.

In FIG. 3, when the steam trigger 680 is depressed, the linkage 681 opens the connection between the dosing chamber 582 and the pressure equalization conduit 760. The water, dripping through the dosing point 700 into the steam chamber 600 and then onto the soleplate 540, is replaced by steam from the soleplate 540. Part of this steam condenses inside the dosing chamber 582 thus creating an under-pressure. When the steam trigger is depressed, the airing means 660 is closed and hence the water reservoir 584 cannot suck in air. As a result, the water in the dosing chamber 582 remains at a constant level thus keeping the steam rate constant for a significant part of the ironing session.

In FIG. 4, when the iron 500 is at rest and the steam trigger 680 is released, the linkage 681 closes the connection between the pressure equalization conduit 760 and the dosing chamber 582. Also when the steam trigger 680 is released, the airing means 660 is opened and air rushes in to compensate the under-pressure that is created due to the steam condensation. This restores the pressure inside the water reservoir 584. As air, which does not condense under these conditions, is used to compensate the under-pressure, a good steaming performance is achieved in subsequent cycles.

The dosing chamber is substantially smaller than that of the water reservoir. It is at least three to eight times lower than that of the water reservoir. The volume of dosing chamber is at least 40 cc to enable steaming for one minute at the steaming rate of 40 gm/min. The wider the dosing chamber, the more constant the steam rate is. The dosing chamber is insert-molded by high temperature plastics such as for example Ryton. The water reservoir can be comprised of any conventional plastic.

The diameter of the dosing point depends on factors such as diameter, length and location of the pressure equalization conduit. It can be experimentally determined for each design of the steam iron.

The length and internal diameter of the pressure equalization chamber are so chosen as to avoid condensation and enable instant pressure equalization with minimum losses and minimum risk of clogging. The internal diameter of the pressure equalization conduit is at least 6 mm for good pressure equalization. The conduit is coated with Teflon to reduce the wetting of the surface and thereby minimizing the condensation.

It is to be understood that although preferred embodiments, specific constructions and configurations, as well as materials, have been discussed herein for devices according to the present invention, various changes or modifications in form and detail may be made without departing from the scope and spirit of this invention. 

1. A steam iron comprising a housing, said housing including a water tank, a steam chamber, a pressure equalization conduit for equalizing steam pressure between said steam chamber and said water tank and a mechanism for selectively allowing air into said water tank through an airing means.
 2. A steam iron of claim 1 wherein said water tank is divided by means of a partition wall into a dosing chamber and a water reservoir.
 3. A steam iron of claim 2 wherein said dosing chamber is at least three to eight times smaller than said water reservoir.
 4. A steam iron of claim 2 comprising a means for communication between said dosing chamber and said water reservoir.
 5. A steam iron of claim 1 wherein said mechanism for selectively allowing air comprises a steam trigger which is arranged to close or open said pressure equalization conduit and said means for communication between said dosing chamber and said water reservoir inversely.
 6. A steam iron of claim 1 wherein said mechanism for selectively allowing air comprises a spring loaded plunger which is arranged to close or open said pressure equalization conduit and said means for communication between said dosing chamber and said water reservoir inversely.
 7. A steam iron of claim 1 wherein said mechanism for selectively allowing air comprises an electronic hand sensor, said electronic hand sensor being arranged to activate an electromechanical device which is arranged to close or open said pressure equalization conduit and said means for communication between said dosing chamber and said water reservoir inversely.
 8. A steam iron of claim 7 wherein said electronic hand sensor is a capacitive or an inductive sensor and/or the like.
 9. A steam iron of claim 1 wherein said mechanism for selectively allowing air comprises a steam trigger which is arranged to close or open said pressure equalization conduit and said airing means inversely.
 10. A steam iron of claim 5 wherein said airing means is arranged to allow air into said water reservoir only when said steam trigger is released. 